Engine Light and No Speedo /Tach.. Ideas?

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Engine Light and No Speedo /Tach.. Ideas?

Postby Brad_91 » Sun Apr 29, 2012 4:08 pm

Hey, I'm hoping this is the right place to post these few recent questions I have...

I was just driving home today from a cottage and my speedo dropped off of the map completely.. It had bounced around a bit in the past but I have never lost it. Around the same time I got the engine light, so I'm assuming they're related :P.
My tachometer has also never worked but I've never seen the engine light because of that.

Anyone know where my problem could be? I have a spare gauge cluster but I dont want to put that in unless all other options have been examined because I don't want to rip the dash apart haha. I've heard it could be a problem with the ECU as well? :shrug:

The car is a 1992 JDM Gt-Four.

Any help/ idea is appreciated! :D
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Brad
1992 Celica GT-Four
~65'000km,
Mods: Turbo-back 3" Exhaust, 17x8 Versus Turismo Rims, Black Rally Armor Mud Flaps, turbo timer, manual boost controller, Whiteline rear swaybar!
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Re: Engine Light and No Speedo /Tach.. Ideas?

Postby lumbercis » Sun Apr 29, 2012 4:51 pm

I don't think it's the cluster. I think it's the speed sensor that plugs into the tranny. If that goes you'll lose speedo (although you should still have tach). The check engine will be from the fact that the ECU is seeing different readings from the wheel speed sensors and the transmission sensor.

If my theory is correct you should check your ECU codes and it should say something about a speed reference signal. Might be something as simple as the speedo cable breaking or maybe the teflon gears on the speed sensor getting worn out. Check codes and go from there.

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Re: Engine Light and No Speedo /Tach.. Ideas?

Postby Brad_91 » Mon Apr 30, 2012 11:10 pm

Thanks for the reply!

Is the sensor in an obvious location if I get under the car? I'll be looking for that bad boy asap to see what i can find.. Will it show any wear or should I try to just replace it to see if the problem stops? I haven't seen the engine light today but the speedo did drop in and out as well as reading incorrectly..
Brad
1992 Celica GT-Four
~65'000km,
Mods: Turbo-back 3" Exhaust, 17x8 Versus Turismo Rims, Black Rally Armor Mud Flaps, turbo timer, manual boost controller, Whiteline rear swaybar!
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1992 Toyota Celica

Re: Engine Light and No Speedo /Tach.. Ideas?

Postby Awesome-Trac » Tue May 01, 2012 3:39 am

If I'm correct you can follow the cable that leads from the firewall right behind where your gauge cluster should be which can lead you to the vss(vehicle speed sensor). What I did was disconnect the speedo cable from the vss and turned it slowly using a power drill to make sure there was nothing wrong with the cable then got up the point where I was going to check the sensor but sold the car before I could diagnosis the problem
-1988 Celica Alltrac (white) Sold
-1988 Celica Alltrac (black) new project
-1990 Corolla sedan (sky blue) totalled by my brother :(
-1990 Celica GT-S hatchback (sky blue) daily driver

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Re: Engine Light and No Speedo /Tach.. Ideas?

Postby Brad_91 » Tue May 01, 2012 7:31 pm

alright cool. I'll try that whenever i get a chance to get under it :)

I haven't seen the engine light for 2 days now but it still doesn't seem right :/. Seems like I'm going more like 80 when it says 40 -50 haha
Brad
1992 Celica GT-Four
~65'000km,
Mods: Turbo-back 3" Exhaust, 17x8 Versus Turismo Rims, Black Rally Armor Mud Flaps, turbo timer, manual boost controller, Whiteline rear swaybar!
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Brad_91
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Location: Ontario, Canada

1992 Toyota Celica

Re: Engine Light and No Speedo /Tach.. Ideas?

Postby lumbercis » Tue May 01, 2012 10:37 pm

in that case it sounds like maybe the cable broke... but do what awesome-trac suggested... look at the firewall and there's an obvious cable coming out from where the back side of the cluster would be if you could see it.

About halfway to the sensor that plugs into the transmission there's a section where you can unscrew the two halves of the cable... be careful if you unscrew this as there is a small metal rod/key in there iirc. Don't lose it. Anyway, if you unscrew that you should lose speedo completely. Make sure you can't pull that cable out or anything, i.e. make sure it isn't broken completely. Do the test awesome-trac suggested to test speedo operation.

If that seems normal then you know the problem is in the other half... i.e. the tranny side... follow the cable down to the transmission and you'll see it go into the tranny. Again, make sure the cable isn't broken. The thing that cable connects to is the sensor. If you unbolt it and pull it out of the tranny you'll see a teflon spiral gear. Check that that gear isn't worn down.

You should find something suspicious by the time you get this far. If all cables and sensor look good that's when I'd try pulling the cluster out.

As always, consult the BGB... it has a decent troubleshooting section in the back.

J
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